Does ANYONE know how many pulses per mile the factory speed sensor puts out?

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05 Liberty Limited CRD, converted to KPA 2863 ball bearing and billet turbo, 50hp injectorsl, complete egr delete, cooling fan delete, weeks intake kit, cummins in tank lift pump, ARP studs, 3" turbo back exhaust, samcos, etecno plugs, GDE trans tune, custom GDE engine tune.

don't know the answer but the tire size will change the results.
open the diff and count the number of teeth on the tone ring..
this will tell you the pulse per revolution..

-dkenny

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84 BB school bus, DD8.2L turbo ->the transmission died..too expensive to fix..it'll be heading to the scrap yard..4/11)..Bus gone to Scarp 8/23/11
06 Liberty CRD
'99 dodge ram 2500 quad cab, 4x4, 24v
all Biodiesel powered when its warm enough

That sensor is used for the abs and odometer, the output speed sensor on the transmission is used for speed. Atleast im pretty sure, the diff sensor went out on my jeep and the speedometer still worked. The odometer quit though.

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05 Liberty Limited CRD, converted to KPA 2863 ball bearing and billet turbo, 50hp injectorsl, complete egr delete, cooling fan delete, weeks intake kit, cummins in tank lift pump, ARP studs, 3" turbo back exhaust, samcos, etecno plugs, GDE trans tune, custom GDE engine tune.

It can also use the front ABS sensors for the speedometer.
I lost a front ABS sensor and the speedo and odo quit.

There is no speed sensor on the transmission.
There IS the transmission output speed sensor but its not used for the speedometer.

Edit:
I really cant remember what happened when my ABS sensor died.
But I do know this, over in the KJ SFA section there has been much discussion about the speed sensors. And there are several guys there who did the SFA swap on a 05/06 and dont have a working speedo.

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U.S. Army Retired

According to factory manual there is actually 2 speed sensors on the transmission, an input speed sensor and an output speed sensor. Says it uses the 2 for transmission purposes.

Anyways, theres also the same sensor on diff and front hubs, do you think that the computer looks at all these sensors collectively and uses them to calculate speed?

Id still like to find out the ppm.

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05 Liberty Limited CRD, converted to KPA 2863 ball bearing and billet turbo, 50hp injectorsl, complete egr delete, cooling fan delete, weeks intake kit, cummins in tank lift pump, ARP studs, 3" turbo back exhaust, samcos, etecno plugs, GDE trans tune, custom GDE engine tune.

I just looked through my printed manual (i waited in staples for an hour as it printed off each page, filled up two 4" binders, $300) and you guys are correct. The speed signal comes from the 3 sensors (2 front wheel sensors and 1 rear wheel sensor on an 05). It is fed 12v and a digital signal comes out.

Seems the system can run on 2 sensors since i lost the rear sensor and all was fine. Occasionally i would lose speedo and cruise but only for a minute at most.

This also jives with why i couldnt find any mention of a speed sensor on the manual trans. It uses the same wheel sensors to keep things simple.

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05 Liberty Limited CRD, converted to KPA 2863 ball bearing and billet turbo, 50hp injectorsl, complete egr delete, cooling fan delete, weeks intake kit, cummins in tank lift pump, ARP studs, 3" turbo back exhaust, samcos, etecno plugs, GDE trans tune, custom GDE engine tune.

I think it uses sensors at the wheels because they'll give you an accurate speed reading regardless of what gearing is selected on the transfer case. Using a sensor on the transmission would mean the speedo would be way, way off when the Jeep is driven in 4-Low.